docs: def from_key_bytes(cls, algorithm, key_bytes):
          """Builds a `Signer` from an algorithm suite and a raw signing key.
  
          :param algorithm: Algorithm on which to base signer
          :type algorithm: aws_encryption_sdk.identifiers.Algorithm
          :param bytes key_bytes: Raw signing key
          :rtype: aws_encryption_sdk.internal.crypto.Signer
          """
          key = serialization.load_der_private_key(data=key_bytes, password=None, backend=default_backend())
          return cls(algorithm, key)